Statistics indicate that three-fourths of American homes have at least one smoke detector. However, the NFPA (National Fire Protection Agency) estimates that one-third of those detectors do not work, often because of dead or missing batteries. If this trend continues, the NFPA predicts that up to one-half of all smoke detectors will be non-operational within 10 years. Industry is aware of the problems associated with smoke detectors and has responded with several safety features that are effective but not flawless as evidenced in the above statistics. This invention addresses specific problems associated with smoke detectors on the market today and offers solutions, in the form of certain innovations that will save many lives.
Modern smoke detectors warn a person when a smoke detector's battery is low by producing a chirping sound once a minute. This chirp continues for approximately a month--when the battery goes dead--or until someone either replaces or removes the battery. In a study conducted by the Dallas Texas Fire Department, people described the low battery indicator as annoying. They removed the battery in order to silence the disruptive chirping and then did not replace it (William Jernigan, Ph.D "Keeping the Smoke Detectors Operational: The Dallas Experience", Fire Journal, July/August 1987, pp 57-63). This has resulted in many deaths. For example, on Nov. 29, 1984, a four-year-old boy was killed when residents removed the smoke detector because it was chirping (William Jernigan, Ph.D "Keeping the Smoke Detectors Operational: The Dallas Experience", Fire Journal, July/August 1987, pp 57-63).
Besides being annoying, other problems exist with the low battery chirping warning. Many elderly or hearing impaired cannot hear the chirping warning and do not know when their batteries need to be replaced. The chirping sound continues until the battery is completely depleted which occurs in about a month. New tenants or vacationers returning after a month away cannot possibly know that a battery is dead since chirping cannot occur without battery power.
Dead batteries probably reflect a lack of regular testing and maintenance, and the problem may be compounded by some individual's unfamiliarity with the meaning of the sounds and signals now used to indicate low battery power (John R. Hall, Jr. "The Latest Statistics on US Home Smoke Detectors" Fire Journal, January/February 1989, pp 39-41). When the low battery warning beep occurs in a conventional smoke detector, a person who has not read the instructions may assume the detector is defective and remove it. Most people are not able to tell if a battery in a conventional smoke detector is low or missing unless they read the directions thoroughly. Often people do not read instructions when installing or using any new product, especially complicated smoke detector instructions.
Smoke detectors batteries are removed when low battery chirping begins and when false alarm conditions occur. Many people also remove batteries from smoke detectors in order to use them in other electronic devices, such as television remote controls and electronic toys. Many people have died because their smoke detectors lacked batteries. A fire claimed the lives of two children and a woman when the smoke detectors in the basement and on the second floor did not operate because they lacked batteries ("Fire Watch--Residential" NFPA Journal September/October 1993 page 36).
Smoke detectors on the market today are supposed to prevent the consumer from closing the battery compartment if there is no battery, but the design is flawed.
A prevalent smoke detector on the market today includes a hinged cover that is attached to the detector's base plate in which the base plate houses the battery and electrical components. The hinged cover is designed so that it can not be closed unless a battery is present. However, the hinged cover can easily be forced into position when no battery is present. Furthermore, when the hinged cover is not in the closed position, there is no visual warning indicating a missing battery, just exposed electronic circuitry. Again, a person may assume the detector to be faulty and remove it completely.
Another smoke detector design includes a battery drawer that slides in and out from the smoke detector in a horizontal motion. The compartment drawer can not be reposition into the smoke detector unless the a battery is present. The door, however, is slightly bigger than the battery and therefore offers no effective visual warning that the battery is missing. Also, there is no warning label present on the drawer.
For smoke detectors in which the battery is mounted in an outside compartment, the safety feature prevents the smoke detector from being mounted at all when there is no battery. Most people will not notice that their smoke detector is missing from the ceiling or wall and will probably not replace the battery.
Another common problem that occurs is misalignment of the battery with the smoke detector's electrical contacts. Misalignment occurs when people do not properly install their battery or when they remove the battery from the smoke detectors contacts in order to silence the low battery chirping or a false alarm.
If a smoke detector's battery has been repositioned so that the battery terminals are not in contact with the battery, the hinged cover or battery compartment can still be closed since the battery is actually present. In the case of the external battery compartment, the detector can still be mounted since the battery is in the compartment.
Thus, the two conventional warning features discussed are not effective when a battery is off its electrical contacts. Manufacturers that sell smoke detectors with a battery included store the battery in the battery compartment, however it is not connected to the smoke detector's battery contacts. Consequently when a person unpacks the smoke detector, he or she will not know that the battery is not connected unless the cover or the battery compartment is removed. This further illustrates the unfriendliness of smoke detectors on the market today.
As stated, chirping cannot occur when a battery is not connected or misaligned with its electrical contacts since there is no battery power. On Nov. 13, 1993, five deaths occurred (three of them under the age of 6) when a smoke detector did not work because, as officials stated, the battery was slightly out of alignment with the contacts (Kenneth J. Tremblay "Catastrophic Fires and Deaths Drop in 1992" NFPA Journal September/October 1993 pp 56-69). No known smoke detector has the ability to warn if a battery is not properly aligned with its electrical contacts.
Various means have been employed to address the low battery warning problems of a battery operated smoke detector. In U.S. Pat. No. 5,053,752 to Epstein issued Oct. 1, 1991, the invention warns if a battery is low by displaying a elongated flexible signal member that would hang down from the smoke detector at eye level. Although this invention warns someone that a battery is low by a visual warning, it does so in a manner that is unpractical. After the member is displayed, a person can easily pull the member, like a string on an overhead light, and remove it from the detector permanently. A person would be inclined to do so since the flexible member is hanging at eye level and possibly obstructing his or her path. Thus, this invention is prone to easy tampering. Tampering of smoke detectors is common (removing good batteries, misaligning the smoke detector's battery with its electrical contacts, forcing the smoke detector's cover to close when no battery is present, etc.). Children would find it easy and amusing to yank on the flexible member to remove it permanently. Moreover, even if a person does replace the battery in the smoke detector, restoring the elongated flexible member would prove to be difficult due to the design of the elongated members housing. To restore the elongated member, a person would have to carefully reel or push the member into the housing. This is inconvenient and encourages the detachment of the elongated flexible member from the housing.